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crazy lawnmower

Discussion in 'Members Lounge' started by mstechca, Jun 21, 2005.

  1. D.J.

    D.J. New Member

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    "I don't know exactly how to test for a spark"

    Unscrew the spark plug, reconnect it to the wire. Then leave it lay where you can see it and pull the string. You should see a blue spark in the gap.

    D.J.
     
  2. zachtheterrible

    zachtheterrible Active Member

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    You have to make sure that the metal body of the spark plug (where it screws in the hole) is touching the body of the lawnmower as well. This will complete the circuit.

    OR

    If the spark plug is in an easy to reach place, take a screwdriver and stick it in the wire that connects to the spark plug, and then take the other metal end of the screwdriver and get it close to the place where the wire usually connects. You should see a spark jump from the screwdriver to the tip of the sparkplug.

    I was bored so i made you a picture :lol: i hope you like it :oops:
     

    Attached Files:

  3. mstechca

    mstechca New Member

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    Why do you care?
    I saw sparks from the spark plug itself when I pulled the cord. I saw a brown spark, and I think I saw a blue one too.

    But my lawnmower still doesn't work, and my grass is growing too tall.

    I think I overloaded it with oil, and then I empty the oil tank because it worked before without oil.

    I still can't figure out why it won't work

    I need a simple solution.

    I want to pull the cord and see it start!
     
  4. dave

    Dave New Member

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  5. mstechca

    mstechca New Member

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    Why do you care?

    I forgot to mention that when I pulled the cord with the spark plug out, the cord was ridiculously easy to pull.

    When the spark plug is in, and I pulled the cord, the cord was somewhat harder to pull. Sometimes, when I tried starting it, it makes one loud putt sound and then shuts off.

    does anyone know of any site with a comprehensive lawnmower troubleshooting, because it still doesn't work.
     
  6. zachtheterrible

    zachtheterrible Active Member

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    Alright, you saw a spark, thats good.

    Its probably hard to pull because remember how there is suction, well the spark plug is blocking that suction making it hard to pull.

    DON'T RUN IT WITHOUT OIL! thats very very very very very bad. Oil is in there to lubricate things and keep the friction down. Too much friction and therefroe heat causes your engine to blow up, not literally but . . .

    Im sure there is a lawnmower forum on the net. there are forums for everything. Just search google. If you can't find that, just go to an engine forum or something. forums are the best.
     
  7. mstechca

    mstechca New Member

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    Why do you care?
    I had my neighbour come over and look at it, and he couldn't even fix it.

    Yes, I did put oil in (again).

    I did notice something which just might make it work.

    When I lifted the engine cover off, I saw what appeared to be what is inside a typical hobby motor, but inversed.

    It seems that the circular thing that turns (along with the blade) when I pull the cord seems to make part of a motor circuit. It seems the other part forms some weird magnet or transformer (its shaped like a magnet) and it is connected to the spark plug. This is before any modifications were made.

    I find that if both the circular piece and the magnet/transformer are attached together, I would have a hard time pulling the cord.

    I'm afraid if they are too far apart, the lawnmower won't start because the electricity cannot pass over.

    Please help me. So far, this place has given me the most answers.
     
  8. zachtheterrible

    zachtheterrible Active Member

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    I believe that is the part that makes the HV. I forget what you call it. As long as you are getting sparks though, I don't think I'd worry about that.

    Well, im stumped, accept for the gas filter . . .
     
  9. Roboticinfo

    Roboticinfo New Member

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    That is the magneto but since it is sparking you could check that one of the list.

    Get a business card and see if you could fit it in under tha magneto.
     
  10. MARINE1142

    MARINE1142 Member

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    Try some WD-40 in the carb not too much but see if it starts then if it does then you have some sort of fuel problem such as carb filters cracked lines. Take the air filter off and spray some in the carb while you are tring to start it.
     
  11. zachtheterrible

    zachtheterrible Active Member

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    mstecha, have you checked the gas filter, and yes, check the fuel lines.

    I think that it is:
    1. gas fitler
    2. fuel lines
    3. carbeurator
    4. air filter (possibly)
     
  12. Roboticinfo

    Roboticinfo New Member

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    It sounds like you guys don't know deep down about the engine,
    You guys are giving simple responses, the engine is made up of alot more parts then you describe. You guys didn't even know what a magneto was until I mentioned it.
     
  13. mstechca

    mstechca New Member

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    Why do you care?
    I took apart the entire lawnmower.

    I think now the only thing that could be causing the problem is the motor circuit. Everything else is fine, and nothing is clogged.
     
  14. Roboticinfo

    Roboticinfo New Member

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    That is not a dc motor circuit!!!!!!!!!!!!!!!!!!, that is a magneto.

    Did you check the valves and see if there is any carbon build up.

    Did you check the flywheel?

    Did you check the connecting rod?

    Did you make sure that the piston go's to top dead center?
     
  15. bryan1

    bryan1 Well-Known Member

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    Hiya mstencha,
    You did say before when you cranked the motor there wasn't much compression also you haven't stated if it's a 2 or 4 stroke motor. If it is a 2 stroke have you been putting a bit of oil with the fuel everytime you refill?
    If there isn't any compression then you need to overhaul the motor, probably not a bad idea if you have it apart. Buy a new piston ring and hone the bore so there isn't any scratches etc. If you need more help just ask mate.

    Cheers Bryan :D
     
  16. Roboticinfo

    Roboticinfo New Member

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    That would not be the case, a minor problem like that will not make it not start.

    Think about it mate
     
  17. mstechca

    mstechca New Member

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    I think mine is a 4-cycle engine. The oil goes in one compartment and the gas goes in another. They are not supposed to be mixed together.

    I do get suction when I cover the spark plug hole with my thumb and pull the cord. I also get suction when I cover the carberator top (the part where the air filter is supposed to attach to).

    It seems that the pistons are OK.

    I oiled the flywheel (or the thing that continuously spins with the blades when the lawnmower runs) with WD-40, and once when I tried starting the engine, a pile of blue smoke went out of the top of the lawnmower.

    It seems that if I can obtain the right distance between the U piece and the flywheel (the two parts of the magneto), then maybe it will start. It seems that the farther apart they are, the less chance it has of starting.

    What amount of tension should I be feeling when I pull the cord slowly with the brakes off?
     
  18. Roboticinfo

    Roboticinfo New Member

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    Did you put a business card under the magneto?
     
  19. pike

    pike Member

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    you think its a 4 stroke motor ey?

    if you remove the exhaust cover and see the combustion chamber itself you have a 2 stroke. you can even see the piston move up and down as you pull the cord. if it's covered by a standalone valve its a 4 stroke.

    http://science.howstuffworks.com/two-stroke1.htm

    heres a nice place to find more info about engines.

    you say it starts for 1/2 a second and then dies yes?? I would think there is a blockage in the fuel line somewhere. It starts on the fuel left in the line (for 1/2 a second) and then dies because of too much fuel resistance. Then it slowly refills the line again because of the low pressure in the line, but too slowly for the engine to operate properly.

    blocked carby ??? blocked fuel line??

    Edit: magneto info herehttp://home.howstuffworks.com/chainsaw5.htm
     
  20. mstechca

    mstechca New Member

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    Why do you care?
    Nothing is blocked. I checked every single piece possible. My mower must be a 4-stroke.

    and how will a business card help me? because I aint taking this thing to a dealer yet.
     
  21. Roboticinfo

    Roboticinfo New Member

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    A business card will show you if the magento is centered with the crank shaft. If you canot fit a business card under the magneto then it means that it is forcing the crank shaft to move slow which means that it will barley start and then shut down.

    If you really knew abou engines then I would believe that you examend everything but since you do not no ways to repair the engine that gives me different thoughts.
     

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